Seismic Audio - 4 Pack of Heavy Duty Swivel Caster Wheels, 4 Inch Non Locking Casters with Top Plate for Pro Audio Gear and Other Heavy Objects Non-Locking Swivel Caster ( 4 Pack) 4" Wheel - 5" From Plate to bottom of Caster Steel Frame Non-Skid Rubber Wheels Holds 500 lbs